High-frequency apparatus



, Aug. 14,A 1928.

F. GUTZMANN HIGH FREQUENCYl APPARATUS Filed Aug. 2e, 192s Patented Aug.14, 1928.

UNITED STATES 1,680,183 PATENT OFFICE.

FRITZ GUTZMAN'N, 0F CHARLOTTENBURG', GERMANY, ASSG-'NOR T0 C. LORENZ AK-TIENGESELLSCHAFT, F BERLIN-TEMPELHOF, GERMANY.

HIGH-FREQUENCY APPARATUS.

Appneafion mea August 2s, 192e, serial No.

The present invention has reference to 1mprovements in high frequencyapparatus, 'and it relates more particularly to means for coolingiron-cored apparatus of this char- 5 acter, especially frequencytransformers.

It is of recognized importance to properly cool electrical a. paratuscontaining magnetically stressedp iron, for the purpose of absorbing ordissipating the heat generated by the losses in the iron and in thewindlng.

For this purpose, as is well known, transformers are bodily immersed ina flowing or stagnant cooling medium, such as oil.

My invention is directed to a method and means for cooling apparatuscontainlng magnetically highly stressed iron, such as for instancefrequency changers used for stepping up a fundamental (natural)frequency to higher frequencies, keying or telephony chokes, and likeapparatus for controlling high frequency currents, in whiclnthe eX-cessive iron heat, due to the high frequencies, must be actively removedto insure efficient operation of the device. o

According to my invention I forclbly cause a cooling medium, liquid orgaseous, to circulate between the iron core to be cooled and itsWinding, so that the iron mass is completely surrounded by the coolingmedium, whereas in the conventional oil baths, the oil reaches the ironsurface only in spots through the interstices 1n the surroundingwinding, leaving the prmclpal heat absorption to outwardly directedconvection through the copper winding.

My invention will readily be understood from a description of theaccompanylng drawing, in which the improvement 1s shown, by way ofexample, as applied to a 4.0 frequency transformer, Fig. l being alongitudinal section and Fig. 2 a cross-section through the arrangement.In Fig. 1 the winding is omitted.

In the two figures the reference' numeral l denotes the annular ironcore formed of thin wires wound upon the cylinder 2, with the windings 3and 1l arranged to form the primary and secondary of a toroidal coil, inwell known manner. The iron core 1 is suitably fioatingly suspendedwithin an annular cooling chamber 4, formed by the inner wall 7 and theouter wall 8, and side walls 9 and l0 respectively, and provided withindus and efflux ports 5 and 6 respectively. The

cooling chamber is preferably made of in- 131,576, and in GermanySeptember 19, .1925.

sulating materialso that the windings 3 and l1 can be applied to itdirectly. The cooling oil is forced in throughV port 5, passes throughthe annular cooling chamber 4: in the direction of the arrows, andissues at 6, and is then preferably cooled and used over again incontinuous circulation. The cooling medium, interposed between the ironcore l and the windings 3 and l1 prevents to a high degree heattransference from iron to winding, and the windin space can thus fullybe made use of wit out having to consider the admission possibility ofthe c001- ing medium to the core through the windin A further advantageis that now 'the loa 4 ing factor of the iron can be enhanced, that isto say the ratio between the'iron crosssection and the windingcross-section, since now the -oil` suiiiciently insulates the ironrelative to the winding, which means also less danger of high strayvoltage.

In addition to cooling the iron core by the positively moved coolingmedium for cooling the iron mass, I immerse the transformer in theconventional oil bath for cooling the winding. The movement of thecooling medium through the cooling chamber surrounding the iron core maybe caused by any suitable means, for instance by an electrically drivencirculatory pump, which drive .with its connections to the coolingchamber form nol part of this invention and thus eed no specialillustration or description ere.

The requirements for high frequency ktransformers differ from those fortransformers adapted for ordinary frequencies, as follows The windingsmust be placed very close to the iron' core, to reduce stray fields. 95

The windings must be well insulated from `the iron core due to the highvoltages involved;

(It so happens that good electric insulators'are usually also good heatinsulators, im@ but this can be turned to advantage because heatinsulation is advisable since the iron core is usually at a hightemperature);

And `the usual materials such as cotton, silk and rubber must beexcluded from the we transformer because they can only carry about C.,just a fraction of the 300 C. at which high frequency cores normallyoperate. v

-Moreover, in order; to reduce the -stray Blf' eld the iron core is alsomade of very small dimensions so as to reduce the overall volume of thetransformer winding to facilitate closeness of spacing.

All of the above diilicult requirements are met by the use of oil ortheelectric and heat insulator and at the same time by the circulation ofthe oil Ato remove the heat resultant from iron losses due to eddycurrents as described in detail above.

. What I claim is 1. In high frequency apparatus, an iron core, acooling chamber spacedly surrounding said core, influx and elux ports insaid chamber, and a Winding surrounding said chamber.

2. In high frequency apparatus, a cooling chamber of insulating materialadapted for the passage therethrough of a cooling medium, influx andeiiux ports in said chamber, an iron core oatingly supported within'saidchamber, and a winding surrounding Said chamber.

3. Al high frequency apparatus comprising windings and an iron` core andhaving a support to space the windings and core apart to permit acooling fluid to be circulated between the iron core and windings inall-over contact with the core surface and having means to keep thecooling ilud out of contact with the winding.

In testimony whereof I aHiX my signature.

FRITZ GUTZMANN.

